Cook's representation believes he should be paid as a receiver, and the NFL Players Association is willing to take up the fight for him. Indications are the Titans weren't up for the fight, which could have gone to arbitration.

At stake was a lot of money — the franchise tag for tight ends in 2013 is $6.066 million. For wide receivers: around $10.537 million.

Cook was drafted as a tight end and is listed on the roster as a tight end. On his official Twitter page, Cook even calls himself a tight end.

The debate, however, is about how the Titans have deployed him.According to Pro Football Focus, of the 485 snaps Cook played last season he lined up in the slot on 276 (56 percent). He was also lined up wide on other plays, which would increase his percentage as a receiver.

Article 9, Section 2 of the NFL's Collective Bargaining Agreement states "that the tender will apply to the position in which the player participated in the most plays."

Cook had 44 catches for 523 yards and four touchdowns last year before suffering a season-ending shoulder injury in Week 13. A third-round pick of the Titans in 2009, he has 131 catches for 1,717 yards and eight touchdowns in four seasons.

NFL teams can designate the exclusive franchise tag for one player scheduled to become an unrestricted free agent. The team must the player a one-year contract for the average of no less than the five highest salaries at his position.

Last year the Titans used the franchise tag on Michael Griffin, but removed it after reaching a long-term contract with the veteran safety.

Last week at the NFL Combine, coach Mike Munchak said the Titans "very strongly" planned to make Cook a major player in their offense this fall.

"We feel he is a big part of us having success, having him in the offense and using him in different ways with the changes we made on the offensive side of the ball," Munchak said. "We feel we can give him an opportunity to catch more balls, be more productive and be more efficient without overworking him at the position."